ZCT Systems Group

ZCT Systems was the company that Greg Zumwalt programmed for and owned starting around 1984-1985, when he was not doing direct contract work for Tandy. ZCT did both ports and original games for Tandy during the mid to late 1980's, and since then has done programming for other systems as well, such as DOS, and hacks on retro systems like the Atari 2600.